1. Field of the Invention
The invention concerns a motor vehicle, especially a convertible with an automobile body, to which are assigned a pair of struts, at least one vibration-selective detection unit for detecting longitudinal stresses of the struts during operation of the vehicle, and at least one actuator for producing a force that counteracts a longitudinal stress.
2. Description of the Related Art
A general problem encountered with motor vehicles is that external excitation of vibrations during driving, say, by driving over uneven roadway features, for example, potholes or bumps, can cause undesired vibrations of the automobile body. Vibrations of this sort in the automobile body reduce driving safety and comfort. This problem is especially pronounced in convertibles with an integral body and frame, which, due to the nonrigid roof that cannot brace the body, especially when the roof is open, have a stability disadvantage compared to closed vehicle superstructures. However, this is basically a problem in all vehicles, including those that do not have an integral body and frame, say, frame vehicles, such as motorcycles or vehicles with an aluminum body, which are wholly or partially supported by a sectional frame.
It is well known that so-called vibration dampers, i.e., damping masses, can be provided to prevent the development of vibrations, which are suitable for damping vibrations of certain frequencies, to which the dampers are tuned. The tuning is possible only for a certain individual frequency. Moreover, adaptation to the given type of vehicle type is necessary, and the arrangement of the dampers in the hollow spaces of the car body is structurally difficult. The dampers themselves must have a high mass, which is at odds with the low vehicle weight and economical operation that are desired.
DE 198 20 617 C2 reveals the possibility of equipping individual, inherently length-variable struts of an integral body and frame or of a vehicle frame with a detection unit for detecting external longitudinal stresses on the given strut, an actuator for producing an active counterforce, and a control unit for the actuator. This makes it possible selectively to counteract the external excitation of vibration with short response times. However, this requires considerable structural expense, since the struts must be variable in length and equipped with the specified functional units.